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51.
Peroxidase-containing enzyme supernatant preparations of tobaccoabscission zone flower pedicel tissue sections of ethylene-treatedand untreated Nicotiana tabacum L. plants were assayed for u.v.absorption spectra with and without the addition of IAA. Theu.v. spectral absorption of peroxidase-catalysed IAA oxidationindicated that there is not an appreciable difference in absorbancepeaks in the ethylene-treated plants compared with untreatedcontrols, in the presence of added IAA; however, the ethylene-treatedtissues alone show different absorption peak values in the 1,2, 3, 4, 4.5, and 5 h samples. These results are discussed inrelation to ethylene-induced peroxidase activity in tobaccoflower pedicel abscission zone tissue homogenates. 相似文献
52.
Thomas, H. 1987. Physiological responses to drought of Loliumperenne L.: Measurement of, and genetic variation in, waterpotential, solute potential, elasticity and cell hydration.J.exp. Bot. 38: 115125. Clonally-replicated genotypes of Loiium perenne L. were grownin a controlled environment. Leaf water potential (w) osmoticpotential (s), turgor potential (p = w s), elasticity(E), leaf hydration (g water per g dry matter, H) and numberof green leaves per tiller (NGL) were measured before and duringa 42 d drought treatment. A simplified method of estimating E (at w < 1?0 MPa) usingonly six measurements was developed to permit a measurementrate of 8 leaves per hour. Measurement errors in all characterswere 3% or less. During drought, w and s (at w = 0?5 MPa) decreased significantly,p and E increased significantly, and H decreased slightly. Plantsize during drought was negatively correlated with s, and Hand positively correlated with p, osmotic adjustment, E andNGL. Measurements made on the genotypes before draughting didnot give a reliable indication of their physiological conditionafter adaptation to drought. Genetically controlled variation (broad sense heritability)of drought-adapted plants for E was 15%, w 23%, s, 34%, p, 35%,H 34% and NGL 64%. The possibilities for, and effectivenessof, divergent selection of genotypes with high and low expressionof the characters are discussed. Key words: Water relations, Lolium, genetic variation 相似文献
53.
The demography of three populations of dandelion 总被引:3,自引:0,他引:3
54.
HENRY M. BUTZEL 《The Journal of eukaryotic microbiology》1968,15(2):284-290
SYNOPSIS. The use of axenic medium permits the study of mating type determination in stock 51 (sensitive) of syngen 4 of Paramecium aurelia. A high frequency of cytoplasmically bridged pairs was correlated with a high frequency of change of mating type following conjugation in axenic medium. The direction of change was predominantly from mating type VII to mating type VIII, suggesting a dominance of type VIII cytoplasm in the clones arising from a mixed cytoplasmic ancestry. No significant effect of either lower temperature or of NaX3 upon the pattern of mating type determination was found. The high frequency of cytoplasmic bridges between conjugants led to the formation of many double or higher multiplex clones. 相似文献
55.
Eight specimens of Sericolophus reflexus (Ijima) were compared with the holotype of Hernandeziana ijimae (Hernandez) to assess suspected synonymy of these taxa. An extensive morphometric analysis of the spicules available in these specimens of variable condition show that the H. ijimae holotype exhibits characters near the centre of the range of S. reflexus. It is concluded that H. ijimae is a junior synonym of S. reflexus , and that the family Corythophoridae de Laubenfels is invalid by preoccupation of its base generic name. 相似文献
56.
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58.
JEAN-LOUIS HENRY JOEL NION 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1970,3(3):213-224
Material from Brittany [Bretagne], France, was used for the revision of two trilobite subgenera. Dalmanitina (Eodalmanitina) Henry, 1965 is raised to generic status and maintained in the 'Dalmanitina group' of the Zeliszkellinae; Phacopidella (Prephacopidella) Destombes, 1963, closely related to Eophacops and Phacopidella , is considered an early representative of the Phacopidellinae. 相似文献
59.
SUMMARY. 1. We studied the effects of seasonal flooding on macro-invertebrate abundance by manipulating water regime and detrital level within three contiguous experimental marshes in Manitoba, Canada, over 2 years. One area was seasonally flooded (standing water present through midsummer) with emergent vegetation left undisturbed throughout the study, one was semipermanently flooded (standing water present through the ice-free season) with the vegetation left undisturbed, and one was seasonally flooded with the vegetation harvested at the end of the first summer.
2. Abundances of frequent macroinvertebrate taxa were compared between the seasonally flooded-undisturbed treatment area and each of the other areas.
3. Densities of total invertebrates and of the dominant taxa (Cladocera, Ostracoda and Culicidae) were reduced dramatically by a year of semipermanent flooding, despite high levels of paniculate organic food resources and low populations of predators. Densities were not reduced by lowering the availability of detritus under seasonally flooded conditions.
4. Taxa unaffected by water regime included Dytiscidae, Corixidae, Chironomidae, Ceratopogonidae and Ephydridae.
5. Semi-permanent flooding may have eliminated environmental cues necessary for oviposition, embryonic development and hatch among dominant taxa. High invertebrate densities in temporary waters may be more dependent upon life history traits of resident fauna than upon habitat features such as food availability or predation pressure. 相似文献
2. Abundances of frequent macroinvertebrate taxa were compared between the seasonally flooded-undisturbed treatment area and each of the other areas.
3. Densities of total invertebrates and of the dominant taxa (Cladocera, Ostracoda and Culicidae) were reduced dramatically by a year of semipermanent flooding, despite high levels of paniculate organic food resources and low populations of predators. Densities were not reduced by lowering the availability of detritus under seasonally flooded conditions.
4. Taxa unaffected by water regime included Dytiscidae, Corixidae, Chironomidae, Ceratopogonidae and Ephydridae.
5. Semi-permanent flooding may have eliminated environmental cues necessary for oviposition, embryonic development and hatch among dominant taxa. High invertebrate densities in temporary waters may be more dependent upon life history traits of resident fauna than upon habitat features such as food availability or predation pressure. 相似文献
60.
DARBYSHIRE B.; HENRY R. J.; MELHUISH F. M.; HEWETT R. K. 《Journal of experimental botany》1979,30(1):109-118
Diurnal changes in non-structural carbohydrates, leaf extension,and leaf cavity CO2 concentrations were determined. Before thestart of the photoperiod total non-structural carbohydrate beginsto accumulate due to an accumulation of glucose and fructose.After the start of the photoperiod total carbohydrate continuesto accumulate but at this time this is due to increasing sucroselevels. The pre- and early-photoperiod accumulation is finite,and a reduction of accumulated carbohydrate occurs before amore sustained increase commences. Utilization of accumulatedcarbohydrate commences at least 3 h before the end of the photoperiod.Leaf extension is constant throughout the dark and photoperiod.The CO2 concentration within the leaf cavity is high at 0·3%,but declines before the start of the photoperiod and immediatelyafter lights-on to about 0·06%, this concentrationbeing maintained throughout the day. A slow accumulation ofinternal CO2 occurs after the end of the photoperiod. 相似文献